26/02/2019 2 min

Giant hogweed: limit its proliferation in order to reduce risks to human health and the environment

Placed on the European Union's list of invasive species of concern, giant hogweed presents risks both to the flora of the environments it colonises and to human health. In response to this observation, ANSES was asked to summarise knowledge regarding this plant and make risk management recommendations. With its expert assessment work completed, the Agency recommends the creation of a monitoring system and the use of available control methods to eradicate giant hogweed populations in high-priority areas.

Brought to France as an ornamental plant species at the end of the 19th century, giant hogweed gradually colonised certain environments to the detriment of the local flora. Giant hogweed is a plant belonging to the carrot family (Umbelliferae) which can reach up to 4 meters in height and whose sap can cause burn-like skin irritations (phyto-dermatitis).

In response to these risks to the environment and human health, the European Commission has included giant hogweed on the list of species of concern under EU Regulation 1143/2014 on the prevention and management of the introduction and spread of invasive alien species. In this context, ANSES was approached by the French Ministries of Health and & social responsibility and Ecological & socially-responsible transition, in order to summarise knowledge of the species with regard to the situation in France, while providing management recommendations specific to the country.

Spread toward the southwest of France is anticipated

New introductions of giant hogweed from its area of origin (the Caucasus) are unlikely, but existing populations of the plant in France or neighbouring countries are significant sources of spread. The species invades environments that have been disturbed by humans (roadsides, abandoned meadows) as well as riverbanks, from where it can easily spread through human activities (transport of soil, seeds-sharing, transport along communication routes, etc.).

Currently present in a large northeastern section of France (particularly in the Hauts-de-France region) as well as in the Alps, giant hogweed is steadily moving towards the southwest, where the climatic conditions for its establishment and an increase in its density are particularly favourable.

Recommendations to reduce risks to health and the environment

Although cases appear to be uncommon in France, hogweed can induce burns (phytodermatitis) caused by contact with its sap. This plant also has a significant local impact on riverbank, grassland and forest-edge flora. Faced with these findings, the Agency recommends:

  • the creation of a national monitoring system for giant hogweed, in order to perform regular updates of both its expansion and risk zoning;
  • that available control methods be used to eradicate top-priority hogweed populations (human population exposure, favourable and minimally invaded areas);
  • that, in cases where eradication is not feasible, initiatives to control giant hogweed should aim to contain or weaken populations by depleting the soil seed bank while preventing plants from fruiting.